Character Name: Malphas......... He goes by "Sebastian Michaelis", though, and I wouldn't be surprised if he picks up other aliases in the course of the game.
Are you okay with her having seen their name at some point, or whenever they meet?: Y
Are you okay with Misa revealing this information to your character?: Y
Are you okay with her revealing this information to others?: Y with caveats... see below
Any extra notes/questions:
SO... Sebastian very intentionally does not ever use his actual name (it being "Malphas" is headcanon on my part, since it's never revealed in the series!). Long story short for why, it's very much in line with the tradition in supernatural stuff of a name having power, so he's not going to be thrilled if she knows it. If she seems confused as to why he's not thrilled, he'll at least explain! And could definitely be convinced that it's not as big of a deal in Horos tbf, but by default, it's his most heavily guarded secret, so he would be Concerned.

I leave the decision of whether you want her to open that can of worms period totally up to you, but he wouldn't get actually do anything about it unless she starts telling it to other people! If she wants to, just hit me up so we can talk it out and make sure we're on the same page. OOC I'm totally fine with it but IC it'll make Sebastian quite hostile, essentially... sweats............. sorry